This invention relates to fluid filters, and more specifically to substantially clog-resistant fluid filters for attachment to the end of a suction pipe, discharge tube and the like, located in a fluid containing tank.
As is well known, suction pipes, discharge tubes and the like, useful for drawing fluids from tanks are typically provided at the tip thereof with a fine mesh or net used as a filter adapted to prevent impurities, contaminates or other undesirable or undissolved particulate material from being entrained by the fluid being drawn. Such filters heretofore known in the art are mostly of the type having a net or mesh-like filter stretched along an opening in such conduits. Fine meshes or nets used as filters are highly susceptible to clogging, and are even more susceptible to damage under conditions of extreme pressure combined with jagged debris caught by the filter. This renders these types of filters of little use in applications such as garden sprayers or recreational fuel tanks, where typically varied and voluminous amounts of debris get into the sprayers or tanks, thereby posing a series threat to the structural integrity of these kinds on filters.
U.S. Pat. No. 4,118,323 to Sugiyama et al., (xe2x80x9cSugiyama ""323xe2x80x9d) disclose a plastic strainer in combination with a suction pipe. The strainer comprises a cylindrical body with a tubular top frame and an non-perforated bottom board that are connected by a plurality of circumferentially spaced support elements. A circular cover that fits the top frame has a center through hole provided with a tubular connector that facilitates insertion of a vacuum pipe into the strainer body. The cover is removably attached to the strainer body by a plurality of nail catches on the top frame that snap into a corresponding plurality of holes in a flange extension of the cover. A fine mesh net is partially embedded in and integrally connected to the top frame, bottom board, and support elements of the strainer body. The maximum depth of penetration of the discharge tube into the strainer frame is determined by an annular bulge on the tube and an annular groove in the top of filter.
U.S. Pat. No. 3,833,124, also to Sugiyama et al.(xe2x80x9cSugiyama ""124xe2x80x9d), disclose an immersion type strainer comprising a filter housing having a top plate with an opening therein, a pipe having a bulge portion, and a hollow cylindrical female piece having a recess portion on its inner surface that is complementary to the bulge portion of the pipe. The cylindrical female piece includes a raised portion at one end and an annular collar that cooperate to clamp the female piece to the top plate of the filter housing when the female piece is fitted in the opening of the top plate.
U.S. Pat. No. 4,411,788 to Kimura (xe2x80x9cKimuraxe2x80x9d) discloses a filter for a gasoline tank that comprises a cylindrical filter body having a base and sidewalls, with a net stretched along the periphery thereof, and a lid to cover the open end of the filter body and provided with an insertion hole for a suction pipe. Located on the base of the filter body are a receiving portion and support pieces that engage the tip of the suction pipe. The ribs have support pieces with a surface that establish the maximum depth of the tube""s penetration into the filter.
The filters disclosed in the above references are not self-supporting structures and rely upon a mesh and a separate mesh support structure in order to form the filtering element. Such separation of components necessitates undesirable assembly, and presents the possibility of disassembly or disconnection problems under physical stress to the filter.
FIGS. 1a and 1b depict typical conventional prior art net or mesh filters 45, such as those used in sprayers and the like, and their relative orientations with respect to the end of a discharge tube 25 in tank 55 containing fluid 65. Either discharge tube (depicted in FIG. 1a) or filter 45 (depicted in FIG. 1b) has a cylindrical stop member (35a,35b respectively) located thereon for preventing discharge tube 25 from extending to the end or bottom 47 of filter 45. Cylindrical stop member 35a,35b functions primarily to space the opening of discharge tube 25 from the bottom 57 of tank 55 so that the opening does not become clogged or blocked with debris, undissolved particulate matter or the like.
However, in an attempt to prevent the end of the discharge tube from clogging with debris, neither of the conventional prior art solutions depicted in FIGS. 1a and 1b locates the end of the discharge tube at or very near the bottom of the tank. By not locating the discharge tube at or very near the bottom of the tank the user is unable to draw any fluid remaining in the bottom of the tank, thereby wastefully and inefficiently leaving fluid behind. Therefore, what is needed is a self-supporting, substantially clog-resistant filter for attachment to the end of a discharge tube located on or very near the bottom of a fluid filled tank, in order to draw fluid remaining in the bottom of the tank.
The present invention comprises a self-supporting, substantially clog-resistant, fluid filter located over an opening at the end of a liquid discharge tube, thereby permitting the opening of the liquid discharge tube to extend substantially to the bottom of the fluid filled tank to be emptied. The filter comprises a cylindrically shaped grid, open at both ends, having a first plurality of substantially parallel ribs crossed by and fastened to a second plurality of substantially parallel ribs at an angle to the first plurality of ribs. Spaces or apertures formed between each adjacent pair of parallel ribs provides passage for liquids to be filtered there through, while each of the ribs provide an obstacle for preventing passage of substantially solid matter that may be intermixed or contaminate the liquid. The filter is considered self-supporting because the ribs that from the filter provide all of the necessary structural strength needed for its support. Additionally, at the end of the filter located nearest the bottom of a fluid filled tank, the invention further provides a circular stop member, referred to herein as a snap-on cap cover element or snap-on cap, having raised radial spacers or lugs that stop or prevent the end of the discharge tube from hitting the bottom circular wall of the cover element. The snap-on cap has clips on its outer diameter that securely attach the cover element to the filter.
It is a further object of this invention to provide improved elements and arrangements thereof for the purposes described which are inexpensive, dependable and fully effective in accomplishing its intended purposes. These and other objects of the present invention will become readily apparent upon further review of the following specification and drawings.